A solution of Pd2(dba)3 (0.08 g, 0.087 mmol) in dry THF (5 mL) was treated with PtBu3 (1.06 mL, 0.351 mmol, 10% in hexanes), followed by compound 3 (0.67 g, 1.757 mmol) in dry THF (5 mL) and LiHMDS (3.51 mL, 3.514 mmol) at room temperature. The resulting mixture was stirred at 100° C. in a seal tube for 3 h. The reaction was brought to room temperature and quenched with TBAF (5 mL, 1 M solution in THF). After stirring for 15 min., solution was basified with 1 N NaOH solution (50 mL) and product was extracted into CH2Cl2 (3×20 mL). The combined CH2Cl2 layer was dried (Na2SO4) and evaporated to obtain the crude product. The crude was purified by column chromatography (2 M NH3 in MeOH:CH2Cl2, 2.5:97.5) to obtain compound 4 (0.4 g, 72%) as a foam.
